The present invention relates to irrigation sprinklers and more particularly to sprinklers rotating about a vertical axis of rotation adapted to irrigate only a portion of a circle surrounding the sprinkler.
Referring first to FIG. 3, a sprinkler of one design wherein the present invention is particularly useful is shown in partially cut-away elevation. The sprinkler, generally indicated as 10, has a hollow cylindrical body 12 having a cylindrical shoulder area 14 at the top thereof. A turbine motor 16 is disposed longitudinally within the cylindrical body 12. Turbine motor 16 has an output shaft 20 connected to a rotating head 22 disposed within shoulder area 14 and having a nozzle opening 24 contained therein. The bottom of body 12 is adapted for connection to a source of water 18 under pressure and contains a turbine blade (not shown) operably connected to the turbine motor 16. When water 18 enters body 12, it passes through the turbine blade causing turbine motor 16 to rotate output shaft 20 and rotate head 22 in combination therewith. Water 18 continues past the turbine motor 16 into the rotating head 22 where it exits through nozzle opening 24 as water stream 26. With nothing more, such a sprinkler 10 would water a circular area as indicated by the total cross-hatched area in FIG. 1.
Often, however, it is desirable to be able to water only a portion of a circular area such as indicated by the semi-circle double cross-hatched in FIG. 1. According to the prior art, in rotating sprinklers such as that indicated as 10 in FIG. 3 and other rotating sprinklers such as the "impulse" type indicated generally as 28 of FIG. 8, complicated mechanisms have been employed to reverse the direction of rotation of the rotating head 22, or the like, in order to sprinkle partial circular patterns.
In large portable agricultural irrigation systems, the sprinklers are moved to various locations throughout the area. Sometimes, it is desired that they sprinkle a circular area being disposed within the interior of the plot being irrigated. At other times, a particular sprinkler is alongside a roadway wherein partial circular watering is desirable to prevent unnecessary and irritating watering of the adjacent roadway. Particularly in such agricultural applications, the necessity for specifically selecting sprinklers or readjusting the pattern is an irrigation, not to mention the higher cost and increased complexity attendant such mechanically reversing sprinklers.
Wherefore, it is the object of the present invention to provide a low cost, simple apparatus for modifying a non-reversing rotating sprinkler to irrigate a selected area in the same manner as if the sprinkler head were reversing.